Duchenne muscular dystrophy is inherited in which pattern, and which sex is most commonly affected?

• A. X-Linked Recessive; Men
• B. Autosomal Recessive; Women
• C. X-Linked Dominant; Men
• D. Autosomal Dominant; Both

Answer: (A)

Duchenne muscular dystrophy is caused by mutations in the dystrophin gene on the X chromosome, so it follows an X-linked recessive inheritance pattern. Because males have only one X chromosome, a single mutated copy will manifest disease, making boys most commonly affected. Females are typically carriers with one normal X compensating, though some carrier females may show mild symptoms due to X-inactivation. Autosomal patterns would affect both sexes more equally, and X-linked dominant would often show affected females more readily or with different patterns; neither matches the classic presentation of Duchenne. Recurrence risk is high for sons of carrier mothers, since each son has a 50% chance of being affected.